docs: def integrate(self):
          """
          Return the object representing the primitive of self over the domain. The
          output starts at zero on the left-hand side of the domain.
          """
          coeffs = self.coefficients()
          a,b = self.domain()
          int_coeffs = 0.5*(b-a)*poly.chebyshev.chebint(coeffs)
          antiderivative = self.from_coeff(int_coeffs, domain=self.domain())
          return antiderivative - antiderivative(a)